Figure 1.

A conceptual scheme for revealing the evolutionary effect regarding niche conservatism or niche divergence on community assembly. The strength of the community–environment relationship can be quantified by explained variance (R²) in multiple linear regression or redundancy analysis. (a) When niches are conserved over evolutionary time, the strength of community–environment relationships would remain constant with broadening taxonomic resolution, as phylogenetically related taxa exhibit similar responses to environmental filtering. (b) Moreover, under strong niche conservatism, the strength of community–environment relationships may increase with broadening taxonomic resolution, especially if broader taxonomic units that combine occurrences and abundances of ecologically equivalent taxa can balance the inherent spatiotemporal randomness of finer units. (c) In contrast, when niches experience quick divergence over evolutionary time, the strength of community–environment relationships would decrease with broadening taxonomic resolution, as each more finely resolved taxonomic unit carries unique responses to the environment. See Supplementary Figure S1 for a conceptual example.